The present disclosure relates to a signal amplifier having an inverted topology.
In general, as demand for wireless communications devices and standards governing the use thereof have increased, demand for multi-band transceivers capable of simultaneously processing signals within various bands in a single portable device has increased.
For example, a wireless local area network (WLAN) may simultaneously use 2.4 GHz and 5 GHz bands, while the domestic Korean long term evolution (LTE) band simultaneously uses the 800 MHz, 900 MHz, 1800 MHz, and 2.1 GHz bands.
Thus, a device capable of transmitting and receiving multi-band signals with a single radio frequency (RF) front-end module is required, and in particular, a technique of processing signals within several frequencies with a single low-noise amplifier (LNA) disposed within a front stage of a receiver is required.
Here, an LNA supporting a concurrent dual-band capable of simultaneously processing signals within two different bands may have a cascode or cascade structure.
In general, an amplifier having a cascode structure includes two transistors stacked between a power source terminal and a ground, and since such an amplifier only has a single current path, only a small amount of current is consumed thereby; however, since such an amplifier includes a common gate amplifier, gain characteristics of which may not be optimal, and a common source amplifier having excellent gain characteristics, gain characteristics thereof require improvement.
Also, such an amplifier having a cascade structure includes at least two-stage amplifying units between an input terminal and an output terminal. The amplifying units in the respective stages may be configured as common source amplifiers having excellent gain characteristics, but two or more current paths thereof consume relatively large amounts of power, requiring improvement in terms of power consumption.
Patent Document 1 relates to a dual-band LNA. This related art document, however, does not disclose technical matters regarding an inverted structure using a common source-type amplifier.